An independent investigation faults Marcellus Shale operators EOG Resources and C. C. Forbes for the well blowout in Clearfield County June 3, which leaked wastewater for 16 hours.

Commissioned by the Department of Environmental Protection and authored by petroleum engineer John Vittitow, the investigation found that the contractors â¿¿lost control of the well while performing post-fracturing well cleanout activities,â¿ according to a DEP statement. Department Secretary John Hanger said the results could have been "catastrophic."

EOG Resources was fined $353,400 and C.C. Forbes $46,600, to cover DEPâ¿¿s costs in responding to the spill and investigating the incident.

â¿¿In addition to the financial penalties, DEP ordered EOG Resources to implement practices and take nine corrective actions to avoid a repeat of this incident. C.C. Forbes was ordered to implement similar practices and to take six corrective actions,â¿ the statement said.

The DEP also sent a letter to all Marcellus Shale drillers, outlining the safety measures it expects companies to have in place.